Aerial system



Dec. 10, 192.5. H. H. BvEmGE Re. 19,784

AERIAL SYSTEM Original Filed Feb. 21, 1931 2 Sheets-Sheet 1 INVENTOR 5 HAROLD H. BEVERAGE ATTORNEY Dec. 10, 1935.. H. H. BEVERAGE R 19,734

AERIAL SYSTEM Original Filed Feb., 21, 1931 2 Sheets-Sheet 2 INVENTOR HAROLD H. EVERAGE 'g mm' ATTORNEY Reissued Dec. 10, 1935 R 19,784

UNITED STATES PATENT OFFICE AERIAL SYSTEM Harold H. Beverage, Riverhead, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Original No. 1,961,604, dated July 24, 1934, Serial No. 511,422, February 21, 1931. Application for reissue May 24, 1935, Serial No. 23,252

Claims. (Cl. 250-20) This invention relates to aerial systems and in through which said inductance is connected to particular to aerial systems to be used in the the metal frame work of the craft on which the vicinity of electrical disturbances as, for instance, receiver is installed. In this modification the on installations adjacent a sparking system such capacity of the aerial to ground and to the source .as is used in aircraft work. of disturbances is balanced by the variable ca- 5 It is well known that if a radio receiver is operpacity in the linear conductor extending towards ated adjacent a source of electrical disturbance the source and by the capacity connecting the as, for instance, near the motor of an airplane, aerial inductance to ground in such a manner as considerable diiliculties are encountered in the to form a bridge circuit having as a diagonal the 0 form of noises, due to electrical disturbances, aerial inductance. Clearly, if this bridge circuit which appear in the indicating device used with is balanced or nearly balanced no potential oscilthe receiver. These electrical disturbances, which lations will appear in the aerial inductance which produce interference in the receiver, may be due forms a diagonal of said bridge due to disturbin part to disturbances impressed in the circuits ances originati a the disturbing ou ce- If 5 of the receiver and in part to disturbances which no potential oscillations at the disturbing fre- 5 afiect the aerial system of the receiver. quency appear in the aerial inductance it iol- Many methods have been tried heretofore to lows that no disturbances will app n the inprevent or eliminate disturbances from being set ductances connected with the receiver nor in the up in a receiver which must be operated adjacent receiver. to a source of electrical disturbances as, for in- In some installations the disturbances may re- 20 stance, adjacent the ignition system of an airsult from a capacity effect between the receiver plane. These schemes generally involve shieldper se and ground, the receiver and the source of ing of the ignition system and the spark plugs disturbances, the aerial and ground and the aerial in addition to shielding of the receiver and filterand the source of disturbances. In such installaing out the disturbances by the use of inductances, tions the effect of the disturbances is eliminated 25 choke coils, condensers, etc. None of these methin accordance with the prese invention by p oods were found to be entirely satisfactory in acviding a linear conductor connected through a tual practice. This is due in part to the fact that condenser to a point between the main aerial and shielding, unless extremely elaborate, does not the aerial inductance in the receiver and extendeliminate the disturbances in the receiver, and ing towards the sourcean amount sufficient when 30 if elaborate is too expensive to be widely used. added to the capacity between the aerial and dis- An object of applicant's invention is to provide turbing source to balance the capacity between signal receiving means which includes means for the source and the receiver while the capacity overcoming the above defects. between receiver and ground and the aerial and Another object of applicants invention is to ground balance or substantially balance each 5 provide a receiving system which includes a novother. In this arrangement the receiver is mainel, though simple and inexpensive, means for pretained at a radio frequency potential with respect venting noises due to ignition systems or other to ground by connecting the receiver through sources from decreasing the clearness of the sigan inductance to the frame of the craft on which 40 nal to be received in the receiver. it is installed. In this arrangement, as in the 40 Briefly, this is accomplished in accordance with prior modification, the inductance in the aerial applicant's novel invention bythe use of a receivcircuit which provides energy for the receiver er having a signal energy absorption means informs the diagonal of a bridge circuit and where eluding means for introducing disturbances from balance is obtained introduces no disturbing oscilthe disturbing source to the aerial system in the lations into the receiver. 45 proper amplitude and phase to counteract dis- In each modification the energizing circuits for turbances reaching the receiver circuits or the the filaments of the tubes may include inducmain aerial system from the source of electrical tances to prevent radio frequencies from the redisturbances. ceiver from passing through the heating battery More in detail, this is accomplished in accordand also in the modification wherein the receiver 50 ance with one modification of applicant's invenis connected through a condenser to the frame to tion by the use of a linear conductor extended toprevent short circuiting of said condenser by the ward the disturbing source and connected through heating circuit between the grounded source and a variable capacity to a point between the aerial the filaments of the tubes which are grounded inductance of the receiver and the condenser to the frame of the aircraft. 55

The general features of the present invention briefly described above, and numerous subsidiary objects and advantages to be gained from the use thereof, will appear from the following detailed description of the invention.

The description will be made with reference to the drawings throughout which like reference numerals indicate like parts and in which:

Figure 1 shows diagrammatically, for purposes of illustration only, an aerial system arranged in accordance with the present invention on an airship;

Figure 2 shows the manner in which the disturbances originating in the ignition system are balanced out by including the aerial inductance in the diagonal of a balanced bridge circuit;

Figure 3 shows more in detail the arrangement of Figure 1;

Figure 3a is a modification of the arrangement shown in Figure 3.

Figure 4 shows a modification ment of the prior figures; while Figure 5 shows the manner in which disturbances which might appear in the aerial system of Figure 4 are balanced out in accordance with the present invention.

Referring in particular to the drawings, I indicates the body of an airship. It will be understood that the invention applies equally well to any system to be used on any installation adjacent a source of electrical disturbances as, for instance, on automobiles, ships, and the like. E is a motor for the aircraft and is taken for purposes of illustration as the source of disturbing electrical energy. A receiver 2 is mounted in the body I. The receiver per se forms no part of the present invention and illustration thereof, detailed in nature, is thought unnecessary. Signal energy is supplied to the receiver by means of a trailing aerial T connected through an inductance L and capacity C1 to ground, which in the present case is the metal framework of the body I. Disturbances originating at the motor E obviously may be induced into aerial T. In order to prevent disturbing oscillations, which would normally appear in L if induced in T from E, from affecting the receiver, applicant proposes to compensate or balance out these oscillations by other disturbing oscillations equal in amplitude but opposite in phase. This is accomplished by the use of a linear conductor D connected through a variable capacity C: to the upper electrode of C1, that is, to the lower potential end of inductance L. This linear conductor D may be extended the desired distance from E to obtain disturbing energy of an amplitude at least as great as the disturbing energy induced in T. The condenser C: allows the enof the arrangeergy induced in D to be shifted to the proper phase and amplitude to oppose the energy induced in T.

The manner in which compensation is effected will be more readily understood by referring to Figure 2 in which inductance L is connected to form the diagonal of a bridge circuit having four arms including capacities C1, C2, C3, C4. C4 represents the capacity between the source E and the aerial T. C: represents the capacity between ground G and the aerial T. C1 is the capacity C1 of Figure 1 connecting the receiver to the frame G while C2 is the capacity C2 in the linear conductor D of Figure 1. If points A and B' on inductance L are made of equal potential with respect to the disturbing oscillations no disturbances will be set up in the receiver 2. This short-circuit condenser C1 of Figures 1 and 2.

This difiiculty is overcome in accordance with the present invention by connecting the filament of the thermionic tube or tubes in the receiver through inductances L1, L2 to the source P. L1,

L: are in parallel with the condenser C1 between the frame of the receiver and the metallic structure G of the aircraft. The inductances L1 and L2 isolate the receiver, that is, allow the receiver tobe raised to a potential above the potential of the frame so that normal operation is obtained and the condenser C1 is not in effect short-circuited.

Where short wave lengths are involved the inductances of the leads between the source P and the filaments of the tubes in the receiver may be sufficient to make the system operative without the assistance of the inductances L1, L2. This depends to some extent on the length of the leads from the source to the filaments.

In actual practice, an arrangement, as illustrated in Figure 3a, may be employed where an exceptional degree of freedom from disturbances is desired. In this arrangement the aerial system is coupled to the receiver by a transformer, the primary winding of which is in the aerial system and the secondary of which is in the input circuit of the first thermionic stage in the receiver. An electrostatic shield S in the form of a grid of wires, as disclosed in Shapiro application #598,731, filed November 3, 1922, which resulted in U. S. Pat. #1,942,575, issued Jan. 9, 1934 is interposed between the primary winding L and secondary winding W of the transformer. The conductors of this grid may be connected together at one end and to ground. This modification is similar in other respects to the arrangement of Figure 3. In operation the inductance L is included in the diagonal of a bridge circuit as in Figure 3. No disturbing oscillations appear at A and B and so no undesired signals are impressed on the receiver. The screen S shields the receiver electrostatically with respect to the antenna system but allows magnetic coupling between the secondary winding W and the primary winding L in order that signal energy may be transferred from the antenna system to the receiver.

In some installations, where the receiver opcrates on high frequencies and is grounded through a comparatively long lead to the frame of the airplane, compensation may be obtained by adjusting the position of the main aerial with respect to the source of the disturbing oscillations, thereby varying its exposure" to said source. This is thought to be due to the fact that sufiicient disturbing noises and oscillations are introduced in the lead between the receiver and the frame to compensate disturbing oscillations introduced in the aerial from the disturbing source. The manner in which this sort of disturbance may be compensated will be understood by referring to Figures 4 and 5 in which the linear conductor D is connected at A to the inductance L and extended more or less in the direction of the source ments have no'bunched inductances.

while the leads between the source P and fila- In Figure an aerial system, effected by electrical disturbances from E in a manner similar to that in which the aerial system of Figure 4 is effected, is connected in a diagonal of a bridge circuit so that oscillations at the disturbing frequencies will not appear at A and B. In Figure 5 inductance L is connected in the diagonal of a bridge, one arm of which is formed by the capacity between the frame G and the receiver. This capacity is represented by C1. Another arm of the bridge is formed by the capacity between the source E and the receiver 2 and represented by C2. A third arm of the bridge includes the capacity between the aerial T and ground as represented by C3, while the fourth arm of the bridge includes the capacity between the aerial T and the source E as represented by 04.. In the present case C4 is insufficient to balance the bridge. Added capacity is provided by the conductor D connected through a capacity C5 to point A in the aerial system and extended toward the source E.

As pointed out in connection with Figures 1 and 2, if the capacities, including C5, are adjusted so C1 divided by C: equals Ca divided by (C4 plus C5) no voltage oscillations will appear across A and B and none will be set up in the receiver.

If lead H of Figure 4 is more than a few inches long it will have a considerable impedance. This has been represented in Figure 5 by bunched inductance H1.

In operation the receiver frame can oscillate up and down with respect to the frame of the airplane by building up a potential across the inductance of the lead H and the inductance of the battery leads N. Since the receiver frame and its associated leads may have a considerable area, the capacity C2 may be larger than capacity C4, that is, the receiver frame may have a greater capacity with respect to the ignition system than the capacity between the antenna and ignition system. If C2 divided by C4 is greater than 01 divided by C3 the frame of the receiver will be raised to a potential higher than the potential of the antenna with reference to the disturbing source. Obviously, the disturbance may be balanced by increasing C4, as set forth above, and as illustrated in Figure 5. This has been accomplished, as pointed out above with reference to Figure 5, by extending conductor D towards the ignition system. The same result can be obtained by putting a condenser in shunt to H1 to add to the capacity of C1 or by. putting a condenser in series with T, thereby decreasing C3. In some cases a balance may be obtained by reeling the antenna in or out slightly, which, in effect, varies C3.

Having thus described my invention and the operation thereof, what I claim is:

1. In an aerial system to be used adjacent a local source of artificial disturbances, a main absorption member inherently responsive to signal energy and to electrical and magnetic disturbances, an inductance therein adapted to be coupled to a receiving circuit, a connection between E. In this arrangement the receiver 2 is connected directly to ground by a conductor H,

said inductance and ground, an auxiliary linear aerial connected to said inductance and extending towards said source, said auxiliary linear aerial being responsive to magnetic and electrical disturbances, and amplitude and phase adjusting 5 means in said auxiliary aerial.

2. Means for preventing disturb g oscillations induced in an aerial system from a source of disturbing oscillations from being set up in the receiver inductance in said aerial system comprising a bridge circuit a diagonal of which includes said receiver inductance, said bridge circuit having four balanced arms, one of which includes the capacity of said aerial to ground, another of which includes the capacity of said aerial with respect to said source and the third of which includes a linear conductor extending from a point on said receiver inductance towards said source.

3. In an aerial system to be used adjacent a local source of artificial disturbances, a main absorption member inherently responsive to signal energy and to electrical and magnetic disturbances, an inductance therein adapted to be coupled to a receiving circuit, a connection between said inductance and ground, including a capacity 5 equal to the inherent capacity between said aerial and ground, and an auxiliary linear aerial conductively connected to said inductance and extended towards said source of disturbances to compensate the direct effect of said source on said aerial system.

4. Means for preventing disturbing oscillations induced in an aerial system including a lumped inductance from a source of disturbing oscillations from setting up in said lumped inductance disturbing currents, which may be transferred to any radio apparatus connected to said aerial, comprising a bridge circuit, a diagonal of which includes said lumped inductance, said bridge circuit having four arms, one of which includes the capacity of said aerial system to ground, another of which includes the capacity of said aerial system with respect to said source of disturbing oscillations, a third of which includes an auxiliary aerial in the field of said source of disturbing oscillations, and a fourth arm of which includes balancing reactance.

5. Means for preventing disturbing oscillations induced in an aerial system from a source of disturbing oscillations from being set up in a reactance connected to said aerial system in which reactance signal energy is to be set up for signalling purposes comprising, a bridge circuit a diagonal of which includes said reactance, said bridge circuit having four balanced arms, one of which comprises the inherent reactance between said aerial system and said source of disturbing oscillations, a second of which arms includes the inherent reactance between said aerial system and ground or equivalent fixed potential structure, a third of which arms comprises ,a reactance between a point on said reactance connected with said aerial system and ground or equivalent fixed potential structure, and a fourth of which arms comprises a variable reactance connected to said reactance connected with said aerial system and extending toward said source of disturbing oscillations.

HAROLD H. BEVERAGE. 

